The VXi’s gummy-bear-like qualities come from its radically soft and sticky MI6 rubber sole. The back story: The producers of Mission Impossible 6 asked Five Ten rubber alchemist Charles Cole if it was possible to make a rubber that could be used to climb glass—something that Tom Cruise does in the movie. Cole said he thought it was, locked himself in his laboratory, and Eureka! Several weeks later he emerged with MI6—so gummy that it does indeed stick to glass.

The story does not specify the angle of the glass. Nor can I report on the movie, since I only watch climbing videos. I can, however, gush about the VXi’s performance on “glassy” footholds, especially on steep terrain.

Take Vote With a Bullet at Maple Canyon. The water-polished cobbles on VWaB are slick as … glass, and since the route is 50 degrees overhanging you can’t exactly weight your feet. The way this shoe glued itself to the cobbles on that route was a game-changer—a letter grade at least. Ditto my home bouldering wall with its ephemeral, rubber-spooged jibs. Again the VXi rules—there are problems on my wall that I can’t do in any other shoe.

I should stress the things this shoe does not do, which is everything not mentioned above (with the exception of gritstone, Fontainebleau, and pure faith-and-friction climbing, where I’m guessing the shoe would be amazing). The VXi is unlined and has no midsole; combine this with a super thin (3.5mm) sole of mushy MI6 rubber and you have a climbing shoe that’s an order of magnitude softer than anything I’ve worn. The VXi does not edge, and it will make your feet ache in any situation where you have to stand hard on a foothold for more than a few seconds. You’d have more joy eating soup with chopsticks than you would face climbing in this shoe.

The VXi has a Clarino synthetic-leather upper, which shouldn’t stretch. Nevertheless, I boldly went down to 8.5 from my street-shoe size of 10. This was a little extreme. The first couple of times I wore the shoe, the only way I could put them on was by wearing plastic grocery-store bags as socks. Unless you enjoy S&M, go down no more than one full size.

My VXi’s have now broken in so that they go on without much struggle. The heel cup is snug and locked on, the low-profile toe box wiggles nimbly into skinny slots and pockets, and the upper is generously randed in MI6 rubber, great for scums and hooking.

For something so flimsy-looking, the VXi is also impressively durable. I’ve sized it wicked small, worn it lots, and its “last” is intact—as aggressively cambered and downturned as the day it came out of the box. A less well-made soft shoe would end up looking like a used condom if you rode it this hard.

Oh, flip! I did it again. Think “gummy bears,” you pervert.

OK ... I adore this shoe for overhanging plastic. Outside, it’s a tool I might only use 10 percent of the time, but I’ll still make room for it in my pack, because when the moment’s right, it's candy.